Veeam Backup for Microsoft 365's auto-update activated via the user interface may fail with:
Offline thumbprint check failed: certificate is invalid.
This issue is fixed in Veeam Backup for Microsoft 365 6.0 Cumulative Patch P20220718 (126.96.36.1990).
To fully fix the updater for next releases, please, manually download and install the patch from KB4285. Once it's set, auto-update must work properly for future versions.
This form is only for KB Feedback/Suggestions, if you need help with the software open a support case